Systems and methods for applying deblocking filters to reconstructed video data

Abstract

This disclosure relates to video coding and more particularly to techniques for performing deblocking of reconstructed video data. According to an aspect of an invention, reconstructed video data having a 4:2:2 chroma format is received and for a four line decision segment corresponding to a vertical deblocking boundary for a chroma component of the video data, a gradient value is computed using samples included in the first and fourth lines.

The invention claimed is: 
     
       1. A method of filtering reconstructed video data, the method comprising:
 deriving a sub width chroma variable based on a chroma format, wherein the sub width chroma variable is set to 2 for a 4:2:0 chroma format and is set to 1 for a 4:4:4 chroma format; 
 for a chroma component of the reconstructed video data with an edge type being a horizontal edge, computing a gradient value as follows, computing a first value using samples included in a first line perpendicular to the horizontal edge, determining whether the sub width chroma variable is equal to 2, computing a second value by using one of: samples included in a fourth line perpendicular to the horizontal edge based on the sub height chroma variable not being equal to 2 or samples included in a second line perpendicular to the horizontal edge based on the sub width chroma variable being equal to 2, and computing the gradient value using the first value and the second value; 
 determining, based on whether or not the gradient value is less than a threshold variable, whether or not to modify a maximum filter length variable from 3 to 1; and 
 filtering the chroma component of the reconstructed video data with the edge type being the horizontal edge based on the maximum filter length variable. 
 
     
     
       2. A device of filtering reconstructed video data, the device comprising one or more processors configured to:
 derive a sub width chroma variable based on a chroma format, wherein the sub width chroma variable is set to 2 for a 4:2:0 chroma format and is set to 1 for a 4:4:4 chroma format; 
 for a chroma component of the reconstructed video data with an edge type being a horizontal edge, compute a gradient value as follows, compute a first value using samples included in a first line perpendicular to the horizontal edge, determine whether the sub width chroma variable is equal to 2, compute a second value by using one of: samples included in a fourth line perpendicular to the horizontal edge based on the sub height chroma variable not being equal to 2 or samples included in a second line perpendicular to the horizontal edge based on the sub width chroma variable being equal to 2, and compute the gradient value using the first value and the second value; 
 determine, based on whether or not the gradient value is less than a threshold variable, whether or not to modify a maximum filter length variable from 3 to 1; and 
 filter the chroma component of the reconstructed video data with the edge type being the horizontal edge based on the maximum filter length variable. 
 
     
     
       3. The device of  claim 2 , wherein the device is a video decoder.